Recently, common rail systems (CRS) have been adopted so as to achieve more precise fuel injection control. A CRS controls fuel injection timing and fuel injection volume by controlling an electromagnetic valve of an injector according to engine rotation speed and loading conditions. With regard to the starting control of the engine having a CRS, an injection start cylinder is determined by a specific crank (TDC) signal and a signal indicating an explosion process. Thus, a fuel injection cylinder is not determined based merely on mechanical characteristics, such as a jerk type; the injection start cylinder is determined via the input of the electric signals.
Accordingly, fuel injection can be started at a first cylinder when signals indicating the TDC and explosion process of the first cylinder are received, and the engine is always started by fuel injection at the first cylinder. As another example, a method is also known for shortening discrimination time by analyzing the explosion process signal of each cylinder.
A construction of an electronic control injection device for an internal-combustion engine whose injection order of cylinders is previously determined is also known. This construction comprises an engine rotation sensor, a cylinder discrimination sensor and a cylinder discrimination part (Patent Literature 1). At the rotation of 720° of crank angle of the engine, the engine rotation sensor generates a rotation pulse signal comprising two toothless pulses distant from each other for 360° of crank angle and a plurality of pulses. The cylinder discrimination sensor generates one pulse at the rotation of 720° of crank angle, and this signal is generated simultaneously with one of the two toothless pulses. The cylinder discrimination part determines the engine cylinder to which fuel shall be injected based on the cylinder discrimination pulse signal at the time of generation of the toothless pulses.
Patent Literature 1: the Japanese Patent Laid Open Gazette Hei. 6-93917